I just bought a new monitor that I think is excellent - second only to Apple Retina (or the über expensive 4K monitors) that is an IPS (in-plane switching) like the Apple displays. It is a 24" HP ZR2440w with 1920x1200, with 350 nits of brightness and 178 degree viewing angle. It lists for $350 on NewEgg (I happened to get it for $302 shipped on a promotion). It had a DVI, HDMI, and DisplayPort inputs, and a four port USB hub. The stand is fully adjustable, and it pivots 90 degrees into a portrait mode. It is LED backlit and sturdy.

It looks bright and clear, and even at 50% brightness, it is brighter and whiter than the already very good display on my iMac. And the HP is matte finish, which is far preferable to the shiny, reflective screens (like the iMac) which are so common today.

When one of my dueling monitors needed to be replaced, I opted to go with a single DELL U2913WM 29" ultra-wide monitor. I bought it new from Newegg for $499 less a $50 coupon. The physical screen area is roughly 27"x12" with a resolution of 2,560 x 1,080. It's a delight to work in front of since you're dealing with a single, uninterrupted desktop instead of two.